1. Field of the Invention
This invention relates to a device for detecting a body such as a moving original or copy paper.
2. Description of the Prior Art
In the rotary press type cameras, copying machines, printing machines, etc., a body such as an original or a sheet of copy paper is moved and by detecting the moving body, a film or photosensitive medium for recording the body is moved or operative timing of various recording means is controlled.
The detecting device of this type has heretofore comprised a light source and a photoreception element opposedly disposed with the path of the body interposed therebetween so that interception of the light from the source by the body moving between the light source and the photoreception element is detected in accordance with a variation in quantity of light received by the photoreception element. According to such method, however, the photoreception element can not efficiently receive the light from the source and this has resulted in a low detection sensitivity and a narrow range of detection for the body, which in turn has led to unreliable detection of the body. There has been another disadvantage that the detection time is delayed when the leading end edge of a rectangular body such as a sheet of paper is inclined with respect to the direction of its movement, namely, when such a body is moving obliquely.
A wide detection range could be attained by providing a multiplicity of light sources and photoreception elements, whereas this would lead to complication and expensiveness of the device. As an alternative method, a pair of reflecting plates has been provided between a light source and a photoreception element so that light from the source has been repetitively reflected between the pair of reflecting plates to thereby cause the reflected light passing across the path of the body to be received by the photoreception element. However, this has offered difficulties in aligning the optic axes of the light source and the photoreception element, which has also led to a disadvantage that much skill is required in assembly of the device.